What determines whether a molecule can pass through the cell membrane?

Three primary factors determine whether a molecule will diffuse across a cell membrane: concentration, charge and size.

What kind of molecules can pass through the plasma membrane of the cells through simple diffusion?

Figure 3.1. 3 – Simple Diffusion Across the Cell (Plasma) Membrane: The structure of the lipid bilayer allows small, uncharged substances such as oxygen and carbon dioxide, and hydrophobic molecules such as lipids, to pass through the cell membrane, down their concentration gradient, by simple diffusion.

Which molecule will cross a cell membrane most easily?

Explanation: Small and simple molecules like water, H2O , can pass through the cell membrane easily as it is partially permeable.

What property of the cell membrane allows some molecules to pass easily through but not?

The cell membrane’s main trait is its selective permeability, which means that it allows some substances to cross it easily, but not others. Small molecules that are nonpolar (have no charge) can cross the membrane easily through diffusion, but ions (charged molecules) and larger molecules typically cannot.

Why is filtration a passive process?

Filtration is another passive process of moving material through a cell membrane. While diffusion and osmosis rely on concentration gradients, filtration uses a pressure gradient. Molecules will move from an area of higher pressure to an area of lower pressure. Filtration is non-specific.

What provides the energy for filtration?

Filtration occurs when blood flows through capillaries. What provides the energy for diffusion? Active transport requires the energy of ATP to moe molecules from an area of lesser concentration to an area of greater concentration.

What is the importance of filtration to human physiology?

In general, filtration refers to the passing of a liquid through a filter. In the human body, the kidney functions as a filter. So, anatomically and physiologically, filtration is a process wherein waste and toxins are removed from the body through glomerulus filtration, which results in urine production.

How do these protein and lipid molecules interact with one another within the cellular membrane?

Membrane proteins in a biological membrane are surrounded by a shell or annulus of ‘ solvent ‘ lipid molecules. These lipid molecules in general interact rather non-specifically with the protein molecules, although a few ‘hot-spots’ may be present on the protein where anionic lipids bind with high affinity.

What is needed in order for diffusion to occur?

Diffusion is the net passive movement of molecules or particles from regions of higher to regions of lower concentration. For diffusion to occur there must be a concentration gradient.

How are the molecules arranged within the membrane?

The phospholipids in the plasma membrane are arranged in two layers, called a phospholipid bilayer, with a hydrophobic, or water-hating, interior and a hydrophilic, or water-loving, exterior. Each phospholipid molecule has a head and two tails.

Why is it important for a cell to regulate what molecules are able to pass into or out of the cell?

Selective permeability is essential to cells’ ability to obtain nutrients, eliminate wastes, and maintain a stable interior environment different than that of the surroundings (maintain homeostasis). The simplest forms of transport across a membrane are passive.